Value Collection 20A120CB 5/16-18 Unc H3 4FL Hss Bottom Tap

Product Description

The VALUE COLLECTION 20A120CB is a straight flute hand bottom tap designed for threading operations that require cutting close to the bottom of a blind hole. Built from high-speed steel (HSS), this tap handles a 5/16-18 UNC thread form with an H3 tolerance class and four flutes. Straight flute taps evacuate chips upward and are suited for use in softer materials such as aluminum, brass, and mild steel. The bottom chamfer geometry allows full threads to be cut as near to the base of a hole as the lead permits, making it the right choice when thread depth is critical and a plug or taper tap cannot finish the job.

This tap is used in general machining, maintenance and repair, and fabrication environments where UNC threads must be chased or cut in through or blind holes. The 5/16-18 size is a common fastener thread found across structural assemblies, equipment housings, and mechanical fixtures. Machinists, toolmakers, and industrial maintenance technicians reach for this tap when finishing blind-hole threads in hand-tapping applications or light machine-tapping setups.

Key Features

• Bottom chamfer cuts full threads to within a few threads of the bottom of a blind hole
• 4-flute straight design provides rigid support and consistent thread form in softer materials
• H3 tolerance class suits standard fit requirements for 5/16-18 UNC threads
• High-speed steel construction withstands moderate heat and wear in hand or low-speed machine tapping
• Single-piece packaging with a minimum order quantity of 1

Compatibility

Designed as an OEM-style replacement or standard tooling option for 5/16-18 UNC hand bottom tapping applications in general machining and maintenance environments.

Installation Notes

This tap is installed by machinists or maintenance technicians using a tap wrench or tap handle in hand-tapping operations, or a drill press and tapping head in light machine use. Always start the tap square to the workpiece and apply consistent, moderate pressure while backing off a quarter turn periodically to break chips. Use an appropriate cutting fluid for the material being tapped to extend tool life and improve thread quality. Secure the workpiece firmly before beginning to prevent movement during the tapping operation.